∂y Implicit Differentiation Calculator (dy/dx)

Differentiate both sides, collect dy/dx and solve — for curves you cannot write as y = f(x).

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Formula at a glance

Implicit Differentiation Calculator: Implicit derivative — dy/dx = −(∂F/∂x)/(∂F/∂y). Example: Circle x² + y² = 25 → dy/dx: dy/dx = −x/y
How the Implicit Differentiation Calculator works: Implicit derivative — dy/dx = −(∂F/∂x)/(∂F/∂y)

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📘 About the Implicit Differentiation Calculator

Some curves, like circles x² + y² = r² or the folium x³ + y³ = 6xy, cannot easily be written as y = f(x). Implicit differentiation finds their slope anyway: differentiate both sides with respect to x, remembering that y depends on x, so every y-term picks up a factor dy/dx by the chain rule.

The calculator moves everything to one side, F(x, y) = 0, and uses dy/dx = −F_x/F_y, where F_x and F_y are partial derivatives. It simplifies the answer, gives the slope and tangent line at a point on the curve, and the second derivative d²y/dx².

🧮 Formula

Implicit derivative
dy/dx = −(∂F/∂x)/(∂F/∂y)
Circle
x² + y² = r² ⇒ dy/dx = −x/y

✏️ Worked examples

Circle x² + y² = 25

You enter
Equation in x and yx^2 + y^2 = 25
Independent variablex
Dependent variabley
You get
dy/dxdy/dx = −x/y
Second derivatived²y/dx² = −x²/y³ − 1/y

dy/dx = −x/y.

Folium of Descartes at (3, 3)

You enter
Equation in x and yx^3 + y^3 = 6xy
Point (optional)x=3, y=3
Independent variablex
Dependent variabley
You get
dy/dxdy/dx = (2y − x²)/(y² − 2x)
Slope at (3, 3)−1
Tangent liney = 6 − x

dy/dx = (2y − x²)/(y² − 2x); slope −1.

🧭 How to use this calculator

What you enter

  • Equation in x and y
  • Point (optional)
  • Independent variable
  • Dependent variable

What you get

  • dy/dx
  • Second derivative

❓ Frequently asked questions

When do I use implicit differentiation?

When y is not isolated — circles, ellipses, curves like xy + sin y = x² — or when it is easier than solving for y.

Why does dy/dx appear next to y terms?

Because y is a function of x: by the chain rule d/dx(y²) = 2y·dy/dx.

What is dy/dx for x² + y² = 25?

−x/y. At (3, 4) the slope is −3/4, so the tangent is y = −3x/4 + 25/4.